Explosive welding of pipe with explosive means

ABSTRACT

A high explosive ring is detonated by placing in contact with the ring a sectional, connected, planar mounting member having a circular opening for receiving the ring of explosive and contacting the outer surface of the ring. Arranged on the mounting member, which may be formed of material destroyed on detonation of the explosive, are arcuate patterns of high explosive formed in a flower-like shape outwardly from the center of the ring at the base of petals of the flower-like shape at a multiplicity of peripherally spaced-apart points, the base and the petals having circular openings. Each petal may be provided with a detonator connected to an electrical source such that on energization of the detonators the strips explode and initiate simultaneously explosion of the ring at each point of contact.

United States Patent [191 Howell et al.

EXPLOSIVE WELDING OF PIPE WITH EXPLOSIVE MEANS Inventors: William G. Howell, Lakewood;

Steve H. Carpenter, Littleton; Henry E. Otto, Denver, all of Colo.

Esso Research and Engineering Company Filed: May 12, 1972 Appl. No.: 252,678

Assignee:

References Cited UNITED STATES PATENTS [111* 3,819,103 June 25, 1974 3,645,435 2/1972 Doherty, Jr. et al 29/4701 X Primary Examiner-J. Spencer Overholser Assistant Examiner-Robert J. Craig Attorney, Agent, or Firm-Thomas B. McCulloch; F. Donald Paris [5 7] ABSTRACT A high explosive ring is detonated by placing in contact with the ring a sectional, connected, planar mounting member having a circular opening for receiving the ring of explosive and contacting the outer surface of the ring. Arranged on the mounting member, which may be formed of material destroyed on detonation of the explosive, are arcuate patterns of high explosive formed in a flower-like shape outwardly from the center of the ring at the base of petals of the flower-like shape at a multiplicity of peripherally spaced-apart points, the base and the petals having circular openings. Each petal may be provided with a detonator connected to an electrical source such that on energization of the detonators the strips explode and initiate simultaneously explosion of the ring at each point of contact.

8 Claims, 13 Drawing Figures EXPLOSIVE WELDING OF PIPE WITH EXPLOSIVE MEANS CROSS-REFERENCES TO RELATED APPLICATIONS This application is related to the following copending commonly assigned applications:

1. Ser. No. 252,820 filed May 12, 1972 in the name of William G. l-lowell'and entitled Explosive Welding of Pipe.

2. Ser. No. 252,641 filed May 12, 1972 in the names of William G. Howell and Robert H. Wittman and entitled Welding of Hollow Cylinders Such as Pipe.

3. Ser. No. 252,821 filed May 12, 1972 in the names of William G. Howell, Theodore A. Espinoza, and Robert H. Wittman and entitled Welding of Pipe by Use of Explosives.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed to explosive welding of pipe. More particularly, the invention is concerned with arrangement of explosive for explosive welding of pipe. In its more specific aspects, the invention is directed to apparatus for explosive pipe welding in which a high explosive in an arcuate pattern is used in explosive welding of pipe.

2. Description of the Prior Art Welding of sections of pipe together by the action of explosives is well known. It has also been taught to use interiorly arranged mandrels in welding of pipe to prevent collapse thereof. The prior art also teaches the use of pipe collars for welding pipe by explosive action. Such collars have been formed to provide an angle with the exterior of the pipe but the collars are usually of the same thickness throughout and so is the explosive employed. Likewise, high explosives have been arranged on the exterior of the collar as a cord which is detonated. None of the prior art, however, teaches or makes obvious an expandable and compressible mandrel which is easily movable through the pipe after weldment of one section to another.

Moreover, the prior art does not teach the use of such a mandrel with a particular type of collar and arrangement of explosive or use of the mandrel, collar, and a particular form of explosive together with an arrangement of explosive to detonate the high explosive on a pipe collar.

Of theprior art considered in respect to the present invention, the following patents were considered: US. Pat. Nos. 2,367,206 (Davis); 3,263,323 (Maher et al. 3,563,713 (Rudd); 3,455,017 (Zondag); and Belgian 655,943. While some of these references including Rudd, Davis, and Zondag contemplate explosively joining abutting pipe ends to a metal collar, none concern themselves with the arcuate high explosive pattern having a plurality of initiation points according to the present invention.

. SUMMARY OF THE INVENTION The present invention may be briefly described and summarized as involving a hollow expandable mandrel which is useful in explosive welding of pipe sections together. In the present invention, the hollow mandrel is placed within abutting pipe sections having a collar circumferentially embracing the abutting ends of the pipe at least adjacent to the center of the collar. The ends of the pipe may be buffed to clean metal. The collar is interiorally fonned to have a tapered shape such that the ends thereof are of a lesser thickness than the center. The outer surface of the collar is cylindrical and on it is placed a formed mass of high explosive which covers the collar and which is layered, stepped, molded, mounded, or cast, or formed in any shape such that the thickness of the high explosive mass is greater at the center thereof than at its outer periphery. Arranged in explosive contact with the high explosive is a high explosive pattern of explosive mounted on a suitable planar surface which may be and preferably is destructive by the explosive. The high explosive mass on the collar is contacted at a plurality of points: on the periphery of the explosive mass by separated or buffered strips of high explosive arranged on the planar surface leading to detonation means connected to a source of electrical energy such that on detonation of the ring or mass the collar is substantially instantaneously driven at a sufficient force against the abutting ends of the pipe sections to weld the inner surface of the collar thereto and weld the sections together; the force of the explosive causes the hollow mandrel segments to move from an expanded position such that it is of a lesser diameter and may be moved in the pipe to the next section to be welded onto the ever-increasing length of pipe line being formed.

VARIABLES OF THE INVENTION The mandrel is suitably formed of at least two pairs of opposing tapered pipe sections. While four sections are preferred and most desirable for 10-14 inch pipe and the like, a greater number of opposing pairs of segments may be used for larger pipe. Likewise, a plate on each end may be used with four segments; a greater even number of pairs of segments may require a greater number of plates to cause the tapered segments to be compressed into a cylindrical shape and expand against the inner surface of the pipe sections to be welded together. Four, six, eight, or a greater number of segments may be used with a plate on one end for each pair of segments. The plates are suitably angularly disposed relative to each other and for two pairs of segments may be arranged with respect to each other. The angles for a greater number of pairs will depend on the number of pairs and generally will be less than 90 relative to each other.

The high explosive used in the mass on the collar and in the pattern may be any one of a number of high explosives such as, but not limited to, Detasheet C which is 63 percent by weight PETN, 7 percent by weight nitrocellulose and 30 percent polymeric materials and has a specific gravity of 1.48, a detonation velocity of about 23,000 feet per second, and is currently supplied on the market in rubbery sheet form, pentaerythritol tetranitate (PETN) with red lead and a binder composed of a mixture of butyl rubber and polymers of ,B-pinene, TNT, cyclomethylene (RDX), Pentolite which is a 50:50 mixture of TNT and PETN, amatol, a 50:50 mixture of ammonium nitrate and TNT, and

other well known high explosives and mixtures thereof 23,000 to about 30,000 feet per second may be used in the pattern and explosives having detonation velocities within the range from about 15,000 to 23,000 feet per second in the mass or ring. However, explosives having detonation velocities within the range of about 15,000 to about 30,000 feet per second may be used in both.

The high explosive shaped or formed or otherwise placed on the collar, such as by casting, may have a thickness at least adjacent its center about 200 percent to about 100 percent of the thickness of the sleeve or collar at least adjacent its center and a thickness adjacent its ends about 200 percent to about 100 percent of the collar at least adjacent the ends of the collar. The high explosive may be shaped, formed, cast, or molded, to be layered, stepped, triangular, conical, truncated conical, or mounded in cross-section.

The planar surface may be formed of plywood and the like, or of a suitable plastic material, or other destructible material of light weight. The surface may be circular with a concentric circular opening therethrough conforming to the outer circumference of the high explosive on the pipe collar and may be made of two or more sections which are easily connectible together with a fastener means which simply may be adhesive tape or latches, and the like.

The size of the pipe which may be welded may vary from about 2 to about 48 inches in diameter with collars corresponding in size to weld the ends of the pipe together, but larger diameters of pipe may be used.

The amount of high explosive to be employed will vary, of course, with the size of the pipe collar and the detonation velocity of the explosive. However, the high explosive ring on the collar may have a thickness at the center of the collar sufficient to provide from about 4 to about 32 grams per square inch down to a thickness of from about 2 to about l6 grams per square inch at the ends or edges of the collar. For example, in welding nominal 12 inch pipe and employing Detasheet C explosive, the explosive would have a thickness at the center of the collar of about to about 12 grams per square inch and at the ends or edges of the collar from about 4 to about 6 grams per square inch.

The collar may have a thickness at the center substantially the same as or slightly larger than the wall thickness of the pipe sections tapering on its inner surface to about one-half the pipe sections wall thickness.

The center inner surface of the collar or sleeve may be from about one-sixteenth inch to about 1 inch in width, while the inner tapered surfaces may each be from about 45 percent to about 48 percent of the length of the collar. For example, a 12-inch pipe may require a collar about 4 inches length while a 48 inch collar may require a collar of about 4 to about 6 inches length. A nominal 2-inch pipe may require a collar of about 2 inches length, whereas pipe of nominal inches diameter may require a nominal 4 inches length collar.

BRIEF DESCRIPTION OF THE DRAWING The present invention will be further described and illustrated by reference to the drawing in which:

FIG. 1 is a sectional view of the mandrel taken along the line 1-1 of FIG. 3;

FIG. 2 is a side elevational view of the mandrel;

FIG. 3 is a front view of the mandrel taken along the lines 33 of FIG. 1;

FIG. 4 is a view of the mandrel taken along the lines 44 of FIG. 1;

FIG. 5 is a view of the mandrel taken along the lines 55 of FIG. 1;

FIG. 6 is a view showing the arrangement taken along the lines 6-6 of FIG. 1 of the tension members not shown in FIG. 1;

FIG. 7 illustrates the mandrel in non-compressed position apart from other appurtenances;

FIG. 8 is a view showing positioning of the mandrel in pipe sections to be welded;

FIG. 9 is a view illustrating the pipe sections of FIG. 8 in position to be welded;

FIG. 10 is a view taken along lines 10-10 of FIG. 9;

FIG. 11 shows the welded pipe sections of FIGS. 8 and 9;

FIG. 12 illustrates the pipe collar of FIGS. 9, l0, and 11 before explosive welding;

FIG. 13 illustrates an enlarged view of pipe collar and explosive of FIGS. 9 and 10.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings and particularly to FIGS. 1 to 7, numeral 11 designates the pipe mandrel formed of tapered hollow segments l2, l3, l4, and 15. The taper of the segments may be at an angle from about 130, but preferably is at an angle of about 78 with the longitudinal axis. Connected to each end of segments 12, 13, 14, and 15 are longitudinal mem bers l6, l6, 17, 17', 18, 18', 19 and 19, each provided with an eye means 16a, 16b, 17a, 17b, 18a, 18b, 19a and 1%, respectively.

Rod members 16 and 16 connect to opposite ends of segment 12 and likewise members 18 and 18 connect to segment 14. Rod members 17 and 17' connect to opposite ends of segment 13 and likewise rod members 19 and 19' connect to segment 15. Rod members 16 and 18 extend through openings 20 and 21 in plate 22, and rod members 17' and 19' extend through openings 23 and 24 in plate 25. The other rod members 17, 19, 16 and 18' are provided for use as will be described.

Passing through central openings in plates 22 and 25 is a threaded longitudinally axially extending rotatable rod member 26 which threadedly engages a nut 27 welded to plate 22. Positioned on rod 26 on opposite sides of plate 25 are nuts 28 and 29, locked in place by lock nuts 28a and 29a, whereby the nuts will rotate with rod 26 and cause longitudinal movement of plate 25. The nuts 28 and 29 also allow adjustment of the plates relative to each other.

The plates 22 and 25 are spaced from their respective segments and this space is provided with resilient pad means 30 and 31 and 32 and 33, the latter of which is shown in dotted lines in FIG. 4. The resilient means may be rubber, springs or other compressible means. It will be seen that plate 22 with pads 30 and 31 operably engage one end of each of the segments 12 and 14, while plate 25 with pads 32 and 33 operably engage one end of each of the segments 13 and 15. The plates 22 and 25 are positioned on rod 26.

Connected to each plate 22 and 25 are members 34 and 35, respectively, on each end of which are yoke members 36 and 37 (FIGS. 1, 2 and 5) in the shape of a cross and formed to carry on their ends rollers or wheels 39 for movement of the mandrel 11 through a pipe section such as 40 shown in dotted line in FIG. 5.

Referring to FIGS. 1 and 4, telescoping members 41 and 42 are connected respectively to plates 22 and 2S and serve to provide stability for the segments 12, l3, l4 and 15, especially when large mandrels are used with large sizes of pipe. It will be noted that the members 41 and 42 are square shaped in cross section and member 42 telescopes within member 41. This provides a spline assembly which extends through the central opening fonned by the segments and allows longitudinal movement of the members 34 and 35 relative to each other. It will also be noted that the end of all the rod members 16-19 are provided with enlarged heads to prevent excess longitudinal retraction of the segments relative to each other.

In FIG. 6, tension means 43, not shown heretofore for reasons of clarity, are connected to eye means 16a, 17a, 18a, and 19a and, of course, while not shown in this view, similar tension means 43 are connected to eyes 16b, 17b, 18b, and 19b. These tension means 43 are provided to maintain and hold the segments 12, 13, 14 and together, especially in their retracted position. The spring members 43 tend to bias the segments toward the center axis of the assembly whereby they do not drag or contact the inside wall of the pipes when they are retracted.

FIG. 7 shows the mandrel 11 in its retracted or nonexpanded position with the segments 13 and 15 moved relative to segments 12 and 14. FIGS. 1 to 4 and 6 show the segments 12-15 in their expanded and locked position.

Referring now to FIGS. 8-13, inclusive, the mandrel 11 is in the pipe section 40 and a collar 45 (FIG. 12) with a layered stack of high explosive such as Detasheet C 46 arranged thereon. It will be noted that the collar 45 is tapered interiorly its ends while the layered stack 46 has its greatest thickness corresponding to the greater thickness of the collar 45. The collar 45 defines angles of about 1 to with the exterior of the pipe sections and 40a with the preferred angle being dependent upon the explosive used. For an angle of 8 an explosive of detonation velocity of approximately 23,000 feet per second is used. A suitable angle is about 5 to about 15.

The ends 40b and 400 of pipe sections 40 and 40a, respectively, are buffed to clean metal for about 2 inches from each of the ends and the ends butted to gether as shown in FIG. 9. The mandrel 11 is then centrally located thereunder with the segments thereof in their retracted position. When it is determined that the pipe sections are accurately aligned and the ends thereof in full abutment, the rod member 26 is rotated by crank rod 26a in one direction to draw the plates 22 and 25 toward each other, thereby expanding the tapered segments 12-15 against the inner wall of each of the pipe sections. At this time the collar with explosive ring 46 is moved on the pipe to the position shown in FIG. 9. After the collar is properly positioned, the rod 26 is rotated in the opposite direction to move the plates 22 and 25 away from the segments a prescribed distance as shown in FIG. 9. The segments will maintain their expanded position against the inner wall of the pipes by means of the locking effect of the taper of the segments, and are in full 360 contact with the pipe wall. This complete contact prevents occurrences of deformities during the explosive welding process.

Thereafter the planar surface 47 with the arrangement of Detasheet C strips 48 on planar surface 47 and detonators 49 are connected to a source of electrical energy not shown by leads 50 and strips 48 are placed in explosive contact with the layered mass 46, as shown in FIGS. 9 and 10, the two sections 47a and 47b being held together by connecting means 47c. The detonators 49 are simultaneously electrically energized and the high explosive mass 46 detonates and causes the collar 45 to be forced against pipe sections 40 and 40a with sufficient impact to cause the sections 40 and 40a to be welded together as shown in FIG. 11 by welding the collar to sections 40 and 40a. It will be noted from FIG. 11 that the force of the impact of the collar 45 against the pipe sections 40 and 40a and mandrel 11 causes the segments 13 and 15 to move relative to segments 12 and 14 diminishing the circumference of the mandrel 11 to its retracted position (FIGS. 6 and 11) and allowing it to be moved to the open end of pipe section 40a for explosive weldment of another pipe section thereon.

The arrangement of high explosive strips 48 on the planar surface or mounting member 47 is in the form of a flower, such as a sunflower, and is formed of petals 51 of explosive strips having circular or other arcuate openings 52 and points 53 to which the detonation means 49 are connected by leads 50. The base 54 of each petal 51 has circular or other shaped openings 55 such that on detonation of the arcuate strips 48 the detonation waves are caused to travel or follow accurate paths to the ring of high explosive. It will be seen that each petal extends from the opening toward the edge of the planar surface mounting member 47 to form the flower-like pattern. The high explosive petals may be mounted on the member 47 by adhesives or other means such as clamps and the like.

The use of arcuate patterns of a flower-like shape is a means for providing instantaneous initiation of detonation of the high explosive mass or ring while providing a means which is perpendicular to the high explosive mass or ring around the circumference thereof. The strips forming the petals of the explosive flower are initiated by near zero function time initiators by providing a detonation means for each petal" of the flower to achieve the instantaneous initiation.

Thus, the present invention is quite important and useful. Pipe sections may be welded together with a minimum expenditure of equipment, effort and time. Pipe sections of 12-14 inches in diameter and of greater or lesser diameter are easily welded together. The invention is, therefore, new, useful and unobvious since heretofore manpower and/or machines were necessary to weld pipe together.

The nature and objects of the present invention having been clearly described and illustrated and thebest mode and embodiment contemplated set forth.

What we wish to claim as new and useful and secure by letters patent is:

1. Apparatus for use in explosive welding abutting ends of hollow cylindrical members which comprises:

an upstanding planar mounting member formed in at least two connectible sections and forming when connected a circular opening and adapted to be mounted in spaced relation about said cylindrical members in substantial alignment with said abutting ends;

means for connecting said sections together for mounting said planar member about said cylindrical members whereby said connected sections have an inner and an outer periphery; means forming a plurality of arcuate patterns of high explosive arranged on each of said sections of said planar member and extending from the inner periphery of the connected sections forming said opening to a plurality of equally spaced-apart initiation points near the outer periphery thereof;

said explosive pattern means being adapted to be explosively connected to an annular band of high explosive located between said planar member and said cylindrical members;

detonation means connected to each of said pattern means at said initiation points; and

means for detonating said detonation means and pattern means and said annular band.

2. Apparatus in accordance with claim 1 in which the pattern means are formed by a plurality of petals of high explosive, each of said petals extending from said inner periphery to said detonation means, said petals each having an opening formed by a pair of spaced arcuate strips connected at one end to define an apex and at the other end by a base adapted to contact said band of high explosive, each base also having a plurality of spaced openings.

3. Apparatus in accordance with claim 2 in which the openings in each of said petals and said base are circular.

4. Apparatus in accordance with claim 2 in which said detonation means is connected to the apex of each petal.

5. Apparatus in accordance with claim 1 in which the arcuate pattern means are formed to enclose a plurality of equally spaced circular spaces about said member such that the detonation waves formed upon detonanon of the patterns follow arcuate paths in the direction from said outer periphery to said inner periphery.

6. Apparatus in accordance with claim 1 in which the high explosive is PETN.

7. Apparatus in accordance with claim 1 in which the high explosive is Detasheet C.

8. Apparatus in accordance with claim 1 including means for adhesively attaching said patterns to said mounting member. 

1. Apparatus for use in explosive welding abutting ends of hollow cylindrical members which comprises: an upstanding planar mounting member formed in at least two connectible sections and forming when connected a circular opening and adapted to be mounted in spaced relation about said cylindrical members in substantial alignment with said abutting ends; means for connecting said sections together for mounting said planar member about said cylindrical members whereby said connected sections have an inner and an outer periphery; means forming a plurality of arcuate patterns of high explosive arranged on each of said sections of said planar member and extending from the inner periphery of the connected sections forming said opening to a plurality of equally spaced-apart initiation points near the outer periphery thereof; said explosive pattern means being adapted to be explosively connected to an annular band of high explosive located between said planar member and said cylindrical members; detonation means connected to each of said pattern means at said initiation points; and means for detonating said detonation means and pattern means and said annular band.
 2. Apparatus in accordance with claim 1 in which the pattern means are formed by a plurality of petals of high explosive, each of said petals extending from said inner periphery to said detonation means, said petals each having an opening formed by a pair of spaced arcuate strips connected at one end to define an apex and at the other end by a base adapted to contact said band of high explosive, each base also having a plurality of spaced openings.
 3. Apparatus in accordance with claim 2 in which the openings in each of said petals and said base are circular.
 4. Apparatus in accordance with claim 2 in which said detonation means is connected to the apex of each petal.
 5. Apparatus in accordance with claim 1 in which the arcuate pattern means are formed to enclose a plurality of equally spaced circular spaces about said member such that the detonation waves formed upon detonation of the patterns follow arcuate paths in thE direction from said outer periphery to said inner periphery.
 6. Apparatus in accordance with claim 1 in which the high explosive is PETN.
 7. Apparatus in accordance with claim 1 in which the high explosive is Detasheet C.
 8. Apparatus in accordance with claim 1 including means for adhesively attaching said patterns to said mounting member. 